3-Amino-4-substituted pyrazole derivatives are used as intermediates in preparing organic compounds, such as pyrazololopyrimidine derivatives. Non-limiting examples of pyrazololpyrimidine derivatives that utilize 3-amino-4-substituted pyrazole derivatives include those having the general structure shown in Formula V:
wherein:
R is H, alkyl, alkenyl, alkynyl, arylalkyl, arylalkenyl, cycloalkyl, cycloalkylalkyl, alkenylalkyl, alkynylalkyl, heterocyclyl, heterocyclylalkyl, heteroarylalkyl (including N-oxide of said heteroaryl), —(CHR5)n-aryl, —(CHR5)n-heteroaryl,
wherein each of said alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocyclyl, and heteroaryl can be unsubstituted or optionally substituted with one or more moieties which can be the same or different, each moiety being independently selected from the group consisting of halogen, alkyl, aryl, cycloalkyl, heterocyclylalkyl, CF3, OCF3, CN, —OR5, —NR5R10, —C(R4R5)p—R9, —N(R5)Boc, —(CR4R5)pOR5, —C(O2)R5, —C(O)R5, —C(O)NR5R10, —SO3H, —SR10, —S(O2)R7, —S(O2)NR5R10, —N(R5)S(O2)R7, —N(R5)C(O)R7 and —N(R5)C(O)NR5R10;
R2 is selected from the group consisting of R9, alkyl, alkenyl, alkynyl, CF3, heterocyclyl, heterocyclylalkyl, halogen, haloalkyl, aryl, arylalkyl, heteroarylalkyl, alkynylalkyl, cycloalkyl, heteroaryl, alkyl substituted with 1-6 R9 groups which can be the same or different and are independently selected from the list of R9 shown below, aryl substituted with 1-3 aryl or heteroaryl groups which can be the same or different and are independently selected from phenyl, pyridyl, thiophenyl, furanyl and thiazolo groups, aryl fused with an aryl or heteroaryl group, heteroaryl substituted with 1-3 aryl or heteroaryl groups which can be the same or different and are independently selected from phenyl, pyridyl, thiophenyl, furanyl and thiazolo groups, heteroaryl fused with an aryl or heteroaryl group,

wherein one or more of the aryl and/or one or more of the heteroaryl in the above-noted definitions for R2 can be unsubstituted or optionally substituted with one or more moieties which can be the same or different, each moiety being independently selected from the group consisting of halogen, —CN, —OR5, —SR5, —S(O2)R6, —S(O2)NR5R6, —NR5R6, —C(O)NR5R6, CF3, alkyl, aryl and OCF3;
R3 is selected from the group consisting of H, halogen, —NR5R6, —OR6, —SR6, —C(O)N(R5R6), alkyl, alkynyl, cycloalkyl, aryl, arylalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl and heteroarylalkyl,
wherein each of said alkyl, cycloalkyl, aryl, arylalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl and heteroarylalkyl for R3 and the heterocyclyl moieties whose structures are shown immediately above for R3 can be unsubstituted or optionally independently substituted with one or more moieties which can be the same or different, each moiety being independently selected from the group consisting of halogen, alkyl, aryl, cycloalkyl, CF3, CN, —OCF3, —(CR4R5)pOR5, —OR5, —NR5R6, —(CR4R5)pNR5R6, —C(O2)R5, —C(O)R5, —C(O)NR5R6, —SR6, —S(O2)R6, —S(O2)NR5R6, —N(R5)S(O2)R7, —N(R5)C(O)R7 and —N(R5)C(O)NR5R6, with the proviso that no carbon adjacent to a nitrogen atom on a heterocyclyl ring carries a —OR5 moiety;
R4 is H, halo or alkyl;
R5 is H, alkyl, aryl or cycloalkyl;
R6 is selected from the group consisting of H, alkyl, alkenyl, aryl, arylalkyl, arylalkenyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl, wherein each of said alkyl, aryl, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl can be unsubstituted or optionally substituted with one or more moieties which can be the same or different, each moiety being independently selected from the group consisting of halogen, alkyl, aryl, cycloalkyl, heterocyclylalkyl, CF3, OCF3, CN, —OR5, —NR5R10, —C(R4R5)p—R9, —N(R5)Boc, —(CR4R5)pOR5, —C(O2)R5, —C(O)R5, —C(O)NR5 R10, —SO3H, —SR10, —S(O2)R7, —S(O2)NR5R10, —N(R5)S(O2)R7, —N(R5)C(O)R7 and —N(R5)C(O)NR5R10;
R10 is selected from the group consisting of H, alkyl, aryl, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl, wherein each of said alkyl, aryl, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, and heteroarylalkyl can be unsubstituted or optionally substituted with one or more moieties which can be the same or different, each moiety being independently selected from the group consisting of halogen, alkyl, aryl, cycloalkyl, heterocyclylalkyl, CF3, OCF3, CN, —OR5, —NR4R5, —C(R4R5)p—R9, —N(R5)Boc, —(CR4R5)pOR5, —C(O2)R5, —C(O)NR4R5, —C(O)R5, —SO3H, —SR5, —S(O2)R7, —S(O2)NR4R5, —N(R5)S(O2)R7, —N(R5)C(O)R7 and —N(R5)C(O)NR4R5; or optionally (i) R5 and R10 in the moiety —NR5R10, or (ii) R5 and R6 in the moiety —NR5R6, may be joined together to form a cycloalkyl or heterocyclyl moiety, with each of said cycloalkyl or heterocyclyl moiety being unsubstituted or optionally independently being substituted with one or more R9 groups;
R7 is selected from the group consisting of alkyl, cycloalkyl, aryl, arylalkenyl, heteroaryl, arylalkyl, heteroarylalkyl, heteroarylalkenyl, and heterocyclyl, wherein each of said alkyl, cycloalkyl, heteroarylalkyl, aryl, heteroaryl and arylalkyl can be unsubstituted or optionally independently substituted with one or more moieties which can be the same or different, each moiety being independently selected from the group consisting of halogen, alkyl, aryl, cycloalkyl, CF3, OCF3, CN, —OR5, —NR5R10, —CH2OR5, —C(O2)R5, —C(O)NR5R10, —C(O)R5, —SR10, —S(O2)R10, —S(O2) NR5R10, —N(R5)S(O2)R10, —N(R5)C(O)R10 and —N(R5)C(O)NR5R10;
R8 is selected from the group consisting of R6, —OR6, —C(O)NR5R10, —S(O2)NR5R10, —C(O)R7, —C(═N—CN)—NH2, —C(═NH)—NHR5, heterocyclyl, and —S(O2)R7;
R9 is selected from the group consisting of halogen, —CN, —NR5R10, —C(O2)R6, —C(O)NR5R10, —OR6, —SR6, —S(O2)R7, —S(O2)NR5R10, —N(R5)S(O2)R7, —N(R5)C(O)R7 and —N(R5)C(O)NR5R10;
m is 0 to 4;
n is 1 to 4; and
p is 1 to 4,
with the proviso that when R2 is phenyl, R3 is not alkyl, alkynyl or halogen, and that when R2 is aryl, R is not
and with the further proviso that when R is arylalkyl, then any heteroaryl substituent on the aryl of said arylalkyl contains at least three heteroatoms, as well as, any solvates, polymorphs, position isomers and stereo isomers of these compounds. These compounds are disclosed in U.S. Pub. No. US 2004/0209878 A1, published on Oct. 21, 2004 and herein incorporated by reference. The compounds of Formula V can be useful as protein kinase inhibitors and can be useful in the treatment and prevention of proliferative diseases, for example, cancer, inflammation and arthritis. These compounds may also be useful in the treatment of neurodegenerative diseases such Alzheimer's disease, cardiovascular diseases, viral diseases and fungal diseases.
US Pub. No. 2004/0209878 A1 discloses a process to prepare 3-amino-4-substituted pyrazole derivatives of the formula
through the general route described below in Scheme 1. Treatment of the
starting nitrile 1 with potassium t-butoxide and ethyl formate gives rise to the intermediate enol 2 which upon treatment with hydrazine gives the desired substituted 3-aminopyrazole 3.
Okazaki et al. (Chem. Pharm. Bull., 46(1) 69-78 (1998) describe a method for synthesizing 3-amino-5-ethyl-1H-pyrazole that comprises adding acetonitrile to a suspension containing sodium amide and liquid ammonia with stirring followed by the addition of methyl propionate. After removing the ammonia, the mixture is subsequently mixed with ethanol and hydrazine hydrate. Okazaki et al. report that the 3-amino-4-ethyl-1H-pyrazole is also made by following this procedure.
Springer et al. (J. Med. Chem., 25 235-242 (1982) disclose an alternative process to prepare 3-amino-4-ethylpyrazole that involves adding ethyl formate and n-butyronitrile to a suspension of sodium metal in anhydrous ether to form alpha-formyl-n-butyronitrile which, in a separate step, was treated with hydrazine hydrate in glacial acetic acid. Springer et al. report a yield of 21%.
Ullas et al. (J. Org. Chem., 53(11) 2413-2418 (1988) and Smirnow and Hopkins (Synthetic Comm. 16(10) 1187-1193 (1986) prepare a 3-amino pyrazole derivative or 5-alkylcytosine derivatives respectively using a cyclization reaction involving hydrazine. JP 10-29980 discloses a 4-step synthetic route to prepare 3-amino-4-alkyl-pyrazoles. In a process for preparing 9-(arylmethyl) derivatives, Montgomery et al. (J. Med. Chem., 36(1) 55-69(1993)) describe a process for synthesizing 2-formyl-3-(het)aryl-propanenitriles from the corresponding 3-aryl- or 3-heteroaryl-propanenitrile by treating the 3-aryl- or 3-heteroaryl-propanenitrile with sodium hydride in THF followed by the addition of ethyl formate.
In view of the importance of pyrazololopyrimidine compounds, new methods for preparing intermediates used in the synthesis of these compounds is always of interest, especially where the novel method is more economical and produces the intermediate in a higher yield than the prior processes.